1965: The United States increases its presence in Vietnam; in addition, bombing of North Vietnam intensifies. By the end of the year, there are 180,000 American troops in Vietnam, and antiwar protest begins in the United States.

1971: The United States begins withdrawing troops from Vietnam. There is widespread antiwar protest. By the end of the year, there are only 140,000 American troops left in Vietnam.

Today: For the United States, the experience in Vietnam is considered a traumatic event in recent history and serves as a measuring stick for involvement in world conflicts.

1965: There are five million color television sets in the United States, but only three networks.

1971: Television is the dominant cultural force in the United States. There are four networks, including public television, and programming is targeted to specific audiences, like children.

Today: With the explosion of cable and satellite television, the major television networks face stiff competition...